Biomass can be used to produce renewable electricity, thermal energy, or transportation fuels (Bio fuels). Biomass is defined as living or recently dead organisms and any byproducts of those organisms, plant or animal. The term is generally understood to exclude coal, oil, and other fossilized remnants of organisms, as well as soils. In this strict sense, biomass encompasses all living things. In the context of biomass energy, however, the term refers to those crops, residues, and other biological materials that can be used as a substitute for fossil fuels in the production of energy and other products. Living biomass takes in carbon as it grows and releases this carbon when used for energy, resulting in a carbon-neutral cycle that does not increase the atmospheric concentration of greenhouse gases.